WASHINGTON – Kris Benson is still a little while away from returning to the Mets. But the injured right-hander made a major stride last night.

Benson, who’s been on the disabled list all season with a strained right pectoral muscle, made his first rehab start for Class-A St. Lucie and was effective. He tossed three scoreless, hitless, walk-less innings against Jupiter, striking out four and throwing 36 pitches (24 for strikes).

“Tremendous,” pitching coach Rick Peterson said.

It was the first time Benson faced opposing hitters since a March 28 spring-training stint against the Cardinals.

Willie Randolph talked to Benson yesterday afternoon before the start and said, “He said he felt great, which is very comforting.”

Peterson said it hasn’t been determined what Benson’s next step will be.

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After playing two straight minor-league games in right field, Mike Cameron (left wrist tendinitis) had a scheduled game off last night. Cameron will remain at St. Lucie for the time being but likely will head to Triple-A Norfolk for games there at some point . . . Kaz Ishii (strained left lat) will throw a bullpen session tomorrow in St. Lucie.

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Kazuo Matsui singled and scored the Mets’ run in last night’s 5-1 loss to the Nationals, extending his hitting streak to eight games. Matsui has hit .357 (10-for-28) during the streak, and before the game credited his recent burst to being “real relaxed going into the batter’s box.” . . . Cliff Floyd extended his hitting streak to 15 games with a 2-for-3 effort that bumped his average to .373 . . . Victor Diaz went 0-for-3 with a walk and is hitless in his past 12 at-bats, dropping his average to .302 . . . When Jose Reyes stole second base in the seventh inning, it snapped a streak of six games without a Met attempting a steal . . . Royce Ring made his major-league debut in the eighth, retiring lefty Terrmel Sledge on a fly ball to left.

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After Jose Guillen homered in the fourth, he was hit by a Heath Bell pitch in the sixth, drawing a warning from home plate ump Brian Gorman. Bell said he didn’t try to hit Guillen on purpose: “I tried to throw a fastball in,” and the pitch just “got away from me.” Randolph said he thought the warning was “ridiculous.” Two innings later, David Wright got hit by Livan Hernandez when the ball grazed his shirt.